Title

Author

Defense Date

2006

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Human Genetics

First Advisor

Dr. Shawn E. Holt

Abstract

It has been shown that the key components of the hsp90 chaperone complex, including hsp90, p23, hsp70, hsp40, and HOP (p60), associate with telomerase; however, their specific roles in telomerase function and tumor progression have not yet been defined. HSF1, the primary mammalian heat shock protein transcription factor, may affect telomerase activity and transformation by regulating the expression of several hsp90 chaperone complex proteins in response to stress as well as regulating the transcription of hTERT, the protein subunit of telomerase.In our in vitro model of prostate cancer progression, as cells progress from immortal but non-tumorigenic (P69) to tumorigenic (M2182) and eventually metastatic (M12) capabilities, both telomerase activity and global chaperone protein levels increase. Our hypothesis is that HSF1 affects telomerase activity directly at the level of transcription and indirectly at the protein level via its regulation of proteins of the hsp90 chaperone complex. Furthermore, upregulation of HSF1 and/or members of the hsp90 chaperone complex directly contribute to prostate cell transformation and that introduction of chaperone-related genes will convert non-tumorigenic prostate cells to a tumorigenic state.We have shown that ectopic overexpression of HSF1 induces increased expression of endogenous hsp90 in P69 cells. Furthermore, telomerase activity in the overexpressing HSF1 cell lines is increased as well and is the end result of two disparate, yet ultimately cooperating pathways. However, the increased telomerase activity does not correlate with increased tumorigenicity.In conjunction with this study, we have overexpressed hTERT in the P69 cell lines and found that telomerase activity is markedly increased in the absence of chaperone upregulation. We propose that the demand for increased folding and stability of the exogenous hTERT leads to a recruitment of telomerase associated chaperone proteins, which can be measured by increased activity after immunoprecipitations and nuclear translocation of hsp90 chaperone complex proteins.Taken together, these projects indicate a significant role for HSF1 and the hsp90 chaperone complex proteins on telomerase activity, and provide evidence that each may be a viable target for therapeutic intervention.